Is Hsp70 a monomer or a dimer


Synonym: heat shock protein 90
English: heat shock protein 90

1 definition

Hsp90 stands for a heat shock protein with a molecular weight of 90 kDa. It belongs to the so-called chaperones.

2 occurrences

Hsp90 is expressed in bacterial and eukaryotic cells, but is not found in archaea. In humans, Hsp90 is one of the most abundant intracellular proteins and, under physiological conditions, makes up about 1-2% of total soluble cellular protein. In the case of cellular stress (e.g. heat), this proportion can increase to 4-6%.

3 genetics

There are different isoforms of Hsp90 that are encoded by 5 genes:

4 structure

Physiologically, Hsp90 is a dimer. An Hsp90 monomer consists of three domains:

Hsp90 forms a multichaperone complex together with Hsp70 and Hop.

5 function

Hsp90 plays an important role in the folding, intracellular transport and degradation of proteins that are no longer needed or damaged. In the latter, it significantly supports the 26S proteasome.

Furthermore, Hsp90 is essential for the function of many proteins, e.g .:

6 clinic

6.1 Oncology

In cancer cells, there is often an increased expression of anti-apoptotic proteins such as EGFR, PI3K and AKT, which are stabilized by Hsp90. In addition, Hsp90 stabilizes mutated proteins such as v-Src, BCR / ABL and mutated p53. The latter is therefore not broken down by the ubiquitin ligase Mdm2. Hsp90 also plays a role in angiogenesis and metastasis of malignancies.

6.2 Pharmacology

In the case of malignancies, Hsp90 inhibitors are being investigated in clinical studies. These include: